What is the difference between a seamless steel pipe and an ordinary steel pipe?

What different steel pipes between seamless steel pipes and common steel pipes are divided into two kinds, seamless steel pipes and welded steel pipes, according to their manufacturing methods. Seamless steel tubes are made of high-quality carbon steel or alloy steel, with hot rolling, cold rolling (pulling). Welded steel tubes are made by rolling into a tube-shaped steel plate to weld against a seam or spiral seam. In terms of manufacturing methods, they are divided into welded steel tubes for low-pressure fluid transportation, spiral welded steel tubes, direct coiled steel tubes, and welded tubes. Seamless steel tubes can be used for various liquids, gas pipes, etc. Welding pipes can be used for water pipelines, gas pipelines, heating pipes, etc. 1, welded steel pipe 1.1 Welded steel pipes for the transport of low-pressure fluids for the welding of low-pressure fluids and galvanized welded steel pipes are made of carbon mild steel and are the most commonly used small-diameter pipes in pipeline engineering. They are suitable for conveying water and gas. Steam and other media, according to the different surface quality, divided into galvanized pipe (commonly known as white iron pipe) and non-galvanized pipe (commonly known as black iron pipe). The inner and outer walls are coated with a zinc protective layer that is about 3% to 6% heavier than non-galvanized ones. According to the different wall thickness of the pipe, it can be divided into three types: thin-walled pipe, ordinary pipe and thickened pipe. Thin-walled tubes are not suitable for conveying media and can be used as a sleeve. 1.2 Straight seam welded steel pipe Straight seam rolled electric welded steel pipe can be divided into electric welded steel pipe and site-used steel plate block volume welded straight seam welded steel pipe. Several wall thicknesses can be made. 1.3 spiral seam welded steel pipe Spiral seam welded steel pipe is divided into automatic submerged arc welded steel pipe and high frequency welded steel pipe. a Spiral seam automatic submerged arc welded steel pipes are classified into two types: Class A pipe and Class B pipe according to the pressure of the medium. A type of pipe is generally welded with common carbon steel Q235, Q235F and general low alloy structural steel 16Mn. B type pipe is welded with Q235, Q235F, Q195 and other steel materials. It is used as low pressure fluid conveying pipe. B. Spiral seam high frequency Welded steel pipe spiral seam high-frequency welded steel pipe, there is no uniform product standard, generally use common carbon steel Q235, Q235F and other steel manufacturing. 2. Seamless steel tubes Seamless steel tubes are divided into hot-rolled tubes and cold-drawn (rolled) tubes according to manufacturing methods. The maximum nominal diameter of the cold drawn (rolled) tube is 200 mm, and the maximum nominal diameter of the hot rolled tube is 600 mm. In pipeline engineering, when the pipe diameter exceeds 57mm, hot-rolled pipes are often used. When the pipe diameter is less than 57mm, cold-drawn (rolled) pipes are often used. Pipeline engineering commonly used seamless steel pipe has the following three kinds: 2.1 General seamless steel tubes General seamless steel tubes are referred to as seamless steel tubes. They are made of ordinary carbon steel, high-quality carbon steel, ordinary low-alloy steel and alloy structural steel. They are used to make liquid pipes or to make structures and parts. Seamless steel tubes are supplied according to their outer diameter and wall thickness, and they have a variety of wall thicknesses under the same outer diameter, and they can withstand a wide range of pressures. The length of the steel pipe is usually 3-12.5m for hot-rolled pipes and 1.5-9m for cold-drawn pipes. 2.2 Seamless steel tubes for low and medium pressure boilers Seamless steel tubes for low and medium pressure boilers are made of No. 10 and No. 20 high-quality carbon steel.